CN108511737B - Nano AZO-coated octahedral-structure lithium nickel manganese oxide composite material and preparation method thereof - Google Patents

Nano AZO-coated octahedral-structure lithium nickel manganese oxide composite material and preparation method thereof Download PDF

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CN108511737B
CN108511737B CN201810585528.8A CN201810585528A CN108511737B CN 108511737 B CN108511737 B CN 108511737B CN 201810585528 A CN201810585528 A CN 201810585528A CN 108511737 B CN108511737 B CN 108511737B
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刘耀春
史灵琪
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Huai'an New Energy Materials Technology Research Institute
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Abstract

The invention discloses a nano AZO-coated octahedral-structure lithium nickel manganese oxide composite material and a preparation method thereof. The nanometer AZO-coated octahedral-structure lithium nickel manganese oxide composite material prepared by adopting a two-step liquid-phase precipitation combined solid-phase sintering method has an excellent microstructure, high specific capacity, good corrosion resistance and excellent electrochemical performance.

Description

Nano AZO-coated octahedral-structure lithium nickel manganese oxide composite material and preparation method thereof
Technical Field
The invention belongs to the technical field of new energy materials, and particularly relates to an aluminum oxide doped zinc oxide (AZO) coated octahedral Lithium Nickel Manganese Oxide (LNMO) composite material and a preparation method thereof.
Background
Electronic equipment is widely applied to various fields of production and life, and a lithium ion battery is mostly used as a power supply of the electronic equipment, so that the energy density of the lithium ion battery determines the cruising ability of the electronic equipment. The anode material is used as a key component of the lithium ion battery, and the energy density of the anode material plays a decisive role in the energy density of the lithium ion battery. Lithium nickel manganese oxide is considered to be a lithium battery positive electrode material with a great application prospect due to higher energy density and excellent low-temperature resistance. However, the lithium nickel manganese oxide also has the defects of poor conductivity, low specific mass capacity and the like, and the preparation of the high-conductivity lithium nickel manganese oxide-based positive electrode material is the key for realizing the industrial application of the lithium nickel manganese oxide.
The aluminum oxide doped zinc oxide (AZO) is a high-conductivity semiconductor functional material, so that the excellent performance of the AZO-doped zinc oxide is widely researched and applied in the fields of various functional materials. The AZO-coated lithium nickel manganese oxide-based composite material obtained by coating AZO on the surface of lithium nickel manganese oxide particles is a lithium battery positive electrode material with excellent performance, and can replace the existing lithium nickel manganese oxide to become a more excellent high-voltage positive electrode material. The AZO coated lithium nickel manganese oxide secondary lithium battery positive electrode material and the preparation method thereof disclosed in the authorization notice No. CN 102983324B are characterized in that an intermediate product lithium nickel oxide is obtained by adopting a spray drying and solid phase sintering method, and then the AZO is coated by directly evaporating liquid to dryness, so that the performance of the formed product needs to be further optimized and improved.
Disclosure of Invention
The invention provides a nano AZO-coated octahedral-structure lithium nickel manganese oxide-based composite material and a preparation method thereof.
The invention is realized by the following technical scheme:
the preparation method of the nanometer AZO-coated octahedral lithium nickel manganese oxide composite material comprises the following preparation steps:
(1) soluble nickel salt and manganese salt are mixed according to the molar ratio of nickel to manganese elements of 1: 3, dissolving in deionized water in proportion, violently stirring at the constant temperature of 25-50 ℃, slowly adding a sodium hydroxide solution with the concentration of 0.5-2 mol/L to adjust the pH value of the solution to 9-12, continuously stirring for 1-4 hours at the constant temperature, and then centrifuging, washing and drying to obtain an intermediate product precursor;
(2) and (2) enabling the molar ratio of the intermediate product precursor obtained in the step (1) to lithium elements of lithium salt to be 1: 1.04-1.1, and calcining, wherein the calcining process comprises the following steps: heating to 400-600 ℃ at the speed of 1-5 ℃/min, and preserving heat for 2-6 hours; then heating to 800-950 ℃ at the speed of 1-5 ℃/min, and preserving heat for 15-25 hours; then cooling to room temperature at the speed of 1-5 ℃/min, and crushing and sieving to obtain octahedral lithium nickel manganese oxide powder;
(3) dissolving soluble zinc salt, aluminum salt and a chelating agent in an ethanol aqueous solution according to a ratio to obtain an AZO solution, wherein the amount of aluminum ion substances accounts for 0.5-3% of the total amount of zinc ions and aluminum ions, and the ratio of the amount of the chelating agent substances to the total amount of zinc ions and aluminum ions is 1-3: 1, the volume ratio of ethanol in the ethanol water solution is less than or equal to 50 percent; dispersing the octahedral lithium nickel manganese oxide powder obtained in the step (2) in the solution according to a proportion, wherein the mass of AZO accounts for 0.2% -2% of that of the octahedral lithium nickel manganese oxide powder, gradually adding an alkali solution into the mixed solution at a constant temperature of 50-80 ℃ to adjust the pH value of the mixed solution to 9-12, continuously stirring at the constant temperature for 1-4 h, and then centrifuging, washing and drying to obtain a final product precursor;
(4) calcining the precursor of the final product obtained in the step (3), wherein the calcining process comprises the following steps: heating to specific 400-500 ℃ from room temperature at the speed of 5-20 ℃/min, preserving the heat for 1-4 hours, and then cooling to obtain the AZO-coated lithium nickel manganese oxide composite material.
In a further preferred embodiment of the present invention, in the step (2), the lithium salt is lithium carbonate, lithium hydroxide, or lithium hydroxide hydrate.
Further preferably, the chelating agent in the step (3) is citric acid or citric acid hydrate.
In the present invention, it is further preferable that the alkali solution in the step (3) is a sodium hydroxide solution, a potassium hydroxide solution, a lithium hydroxide solution, or a mixture of two or three solutions.
The invention also provides a nano AZO-coated octahedral-structure lithium nickel manganese oxide composite material prepared by the preparation method according to any one of claims 1 to 4.
Compared with the prior art, the invention has the following obvious advantages:
1. the nanometer AZO-coated octahedral lithium nickel manganese oxide composite material has excellent morphology and excellent electrochemical performance; simple process, easy operation and low cost.
2. The preparation method adopts coprecipitation and solid phase sintering to prepare the octahedral structural lithium nickel manganese oxide powder, the coprecipitation method adopts a chemical method of adding a precipitator into a solution to precipitate a solid precursor, the obtained intermediate has high activity, an octahedral structural material is easy to obtain in the calcining process, and the octahedral structural material has better mechanical and electrochemical properties. The AZO coated lithium nickel manganese oxide secondary lithium battery positive electrode material and the preparation method thereof disclosed in CN 102983324B are characterized in that the lithium nickel manganese oxide is prepared by adopting a spray drying and solid phase sintering method, the spray drying belongs to a physical method, only nickel and manganese are mixed, the reaction needs to be generated in subsequent calcination, an octahedral structure is not easily formed in the calcination process, and the lithium nickel manganese oxide prepared by the method has a non-octahedral structure.
3. The ZAO coating adopts an in-situ precipitation method of adding a precipitator and low-temperature calcination and pouring (400-. The AZO coating adopts a method of directly evaporating liquid to dryness, then presintering at 700 ℃ in 500-plus-material mode, and then calcining at 900 ℃ in 700-plus-material mode, wherein the coating effect is far lower than that of the AZO coating lithium nickel manganese oxide lithium secondary lithium battery anode material disclosed by CN 102983324B and the preparation method thereof.
Drawings
FIG. 1 is an X-ray diffraction diagram of a nano AZO-coated octahedral-structure lithium nickel manganese oxide composite material prepared in examples 1 to 4;
FIG. 2 is a scanning electron microscope image of the nano AZO-coated octahedral-structure lithium nickel manganese oxide composite material prepared in example 1;
FIG. 3 is a graph showing cycle characteristics of samples obtained in examples 5 to 8 and comparative example 1 at different magnifications at room temperature;
FIG. 4 is a graph showing cycle characteristics at high temperature and high current of the samples obtained in examples 5 to 8 and comparative example 1.
Detailed Description
The present invention will be described in further detail below, and the conditions used in the examples can be further adjusted according to the actual circumstances, but the present invention is not limited to the examples.
Example 1
1. Nickel sulfate hexahydrate and manganese sulfate monohydrate according to the mass ratio of nickel to manganese elements of 1: dissolving 3 in proportion in 50mL of deionized water, slowly adding 1mol/L sodium hydroxide solution at 30 ℃ under the condition of vigorous stirring until the pH value is 11, continuously stirring for 2 hours at constant temperature, and then centrifuging, washing and drying to obtain an intermediate product precursor;
2. and (2) mixing the intermediate product precursor obtained in the step (1) with lithium elements of lithium carbonate according to a molar ratio of 1: 1.04, heating to 500 ℃ at a heating rate of 5 ℃/min, and keeping the temperature for 3 hours; then raising the temperature to 850 ℃ at the heating rate of 2 ℃/min, and preserving the heat for 20 h; finally, cooling to room temperature at the speed of 2 ℃/min; crushing and sieving to obtain an octahedral lithium nickel manganese oxide powder intermediate product;
3. zinc acetate, aluminum nitrate nonahydrate and citric acid monohydrate are taken as raw materials according to Zn2+:Al3+Citric acid is 0.98: 0.02: 1 into 50mL of an aqueous ethanol solution (ethanol: water = 1: 1); mixing the intermediate product obtained in the step (2) with nickel according to AZOThe mass ratio of lithium manganate is 0.003: 1, slowly adding 1mol/L lithium hydroxide solution until the pH value of the solution is 11 in a constant-temperature water bath at 60 ℃ under the condition of vigorous stirring, then continuously stirring for 2 hours, and then centrifuging, washing and drying to obtain a final product precursor;
4. and (4) heating the precursor obtained in the step (3) to 450 ℃ at a heating rate of 10 ℃/min, preserving the temperature for 2 hours, calcining, and naturally cooling to obtain the nano AZO-coated octahedral-structure lithium nickel manganese oxide composite material. Fig. 2 is a scanning electron microscope image of the nano AZO-coated octahedral lithium nickel manganese oxide composite material prepared in this example.
Example 2
1. Nickel sulfate hexahydrate and manganese sulfate monohydrate according to the mass ratio of nickel to manganese elements of 1: dissolving 3 in proportion in 50mL of deionized water, slowly adding 1mol/L sodium hydroxide solution under the conditions of 20 ℃ and vigorous stirring until the pH value is 12, continuously stirring for 3 hours at constant temperature, and then centrifuging, washing and drying to obtain an intermediate product precursor;
2. and (2) mixing the intermediate product precursor obtained in the step (1) with lithium elements of lithium carbonate according to a molar ratio of 1: 1.04, heating to 400 ℃ at a heating rate of 4 ℃/min, and keeping the temperature for 5 hours; then, the temperature is raised to 950 ℃ at the heating rate of 4 ℃/min, and the temperature is kept for 15 h; finally, cooling to room temperature at the speed of 4 ℃/min; crushing and sieving to obtain an octahedral lithium nickel manganese oxide powder intermediate product;
3. zinc acetate, aluminum nitrate nonahydrate and citric acid monohydrate are taken as raw materials according to Zn2+:Al3+Citric acid is 0.99: 0.01: 1 into 50mL of an aqueous ethanol solution (ethanol: water = 1: 1.5); and (3) enabling the intermediate product obtained in the step (2) to be mixed according to the mass ratio of AZO to nickel lithium manganate of 0.02: 1, slowly adding 1mol/L sodium hydroxide solution until the pH value of the solution is 9 under the conditions of 50 ℃ constant-temperature water bath and vigorous stirring, then continuously stirring for 4 hours, and then centrifuging, washing and drying to obtain a final product precursor;
4. and (4) heating the precursor obtained in the step (3) to 500 ℃ at a heating rate of 20 ℃/min, keeping the temperature for 4 hours, calcining, and naturally cooling to obtain the nano AZO-coated octahedral-structure lithium nickel manganese oxide composite material.
Example 3
1. Nickel sulfate hexahydrate and manganese sulfate monohydrate according to the mass ratio of nickel to manganese elements of 1: dissolving 3 in proportion in 50mL of deionized water, slowly adding 1mol/L sodium hydroxide solution at 30 ℃ under the condition of vigorous stirring until the pH value is 11, continuously stirring for 2 hours at constant temperature, and then centrifuging, washing and drying to obtain an intermediate product precursor;
2. mixing the intermediate product precursor obtained in the step (1) with lithium element of lithium hydroxide monohydrate in a molar ratio of 1:1.1, uniformly mixing, heating to 500 ℃ at a heating rate of 5 ℃/min, and keeping the temperature for 3 hours; then raising the temperature to 800 ℃ at the temperature rise speed of 2 ℃/min, and preserving the heat for 25 h; finally, cooling to room temperature at the speed of 2 ℃/min; crushing and sieving to obtain an intermediate product;
3. zinc nitrate, aluminum nitrate nonahydrate and citric acid are taken as raw materials according to Zn2+:Al3+Citric acid is 0.98: 0.02: 2 into 50mL of an aqueous ethanol solution (ethanol: water = 1: 2); and (3) enabling the intermediate product obtained in the step (2) to be mixed according to the mass ratio of AZO to lithium nickel manganese oxide of 0.003: 1, slowly adding 1mol/L sodium hydroxide solution until the pH value of the solution is 9 under the conditions of 80 ℃ constant-temperature water bath and vigorous stirring, then continuously stirring for 10 hours, and then centrifuging, washing and drying to obtain a final product precursor;
4. and (4) heating the precursor obtained in the step (3) to 400 ℃ at a heating rate of 5 ℃/min, keeping the temperature for 1 hour, calcining, and naturally cooling to obtain the nano AZO-coated octahedral-structure lithium nickel manganese oxide composite material.
Example 4
1. Nickel sulfate hexahydrate and manganese sulfate monohydrate according to the mass ratio of nickel to manganese elements of 1: dissolving 3 in proportion in 50mL of deionized water, slowly adding 1mol/L sodium hydroxide solution at 30 ℃ under the condition of vigorous stirring until the pH value is 9, continuously stirring for 2 hours at constant temperature, and then centrifuging, washing and drying to obtain an intermediate product precursor;
2. mixing the intermediate product precursor obtained in the step (1) with lithium elements of lithium hydroxide monohydrate according to a molar ratio of 1:1.1, uniformly mixing, heating to 500 ℃ at a heating rate of 5 ℃/min, and keeping the temperature for 3 hours; then raising the temperature to 850 ℃ at the heating rate of 2 ℃/min, and preserving the heat for 20 h; finally, cooling to room temperature at the speed of 2 ℃/min; crushing and sieving to obtain an octahedral lithium nickel manganese oxide powder intermediate product;
3. zinc nitrate, aluminum nitrate nonahydrate and citric acid monohydrate are taken as raw materials according to Zn2+:Al3+Citric acid is 0.98: 0.02: 1 into 50mL of an aqueous ethanol solution (ethanol: water = 1: 1); and (3) enabling the intermediate product obtained in the step (2) to be mixed according to the mass ratio of AZO to nickel lithium manganate of 0.007: 1, slowly adding 1mol/L lithium hydroxide solution until the pH value of the solution is 11 in a constant-temperature water bath at 80 ℃ under the condition of vigorous stirring, then continuously stirring for 3 hours, and then centrifuging, washing and drying to obtain a final product precursor;
4. and (4) heating the precursor obtained in the step (3) to 500 ℃ at a heating rate of 10 ℃/min, keeping the temperature for 2 hours, calcining, and naturally cooling to obtain the nano AZO-coated octahedral-structure lithium nickel manganese oxide composite material.
As can be seen from fig. 1, in examples 1 to 4, the samples obtained according to the experimental route designed by us showed very high purity without the existence of impurity peaks in their X-ray diffraction patterns.
Example 5
Mixing the sample prepared in example 1 with conductive carbon black super P and a binder PVDF according to a ratio of 8:1:1, dissolving the mixture in N-methylpyrrolidone (NMP), uniformly stirring the mixture, coating the mixture on an aluminum foil to prepare a positive plate, drying the positive plate in a vacuum oven at 120 ℃ for 12 hours, and assembling the dried positive plate, a negative electrode prepared from a metal lithium plate, a polypropylene diaphragm and an electrolyte in a glove box filled with high-purity argon to obtain the CR2032 type button experimental battery.
The charging multiplying power is 0.1C, the discharging multiplying power is 0.1C, 0.2C, 0.5C, 1C, 3C, 5C and 10C respectively, and the charging and discharging voltage interval is between 3 and 4.9 volts. The supporting electrolyte in the electrolyte is LiPF6The solvent is formed by mixing Ethylene Carbonate (EC) and diethyl carbonate (DEC) according to the volume ratio of 1:1, the concentration of the electrolyte is 1mol/L, and the battery test temperature is highThe temperature is room temperature.
Example 6
The sample prepared in example 2 was mixed with conductive carbon black super P and binder PVDF in a ratio of 8:1:1, and the rest was as in example 5.
Example 7
The sample prepared in example 3 was mixed with conductive carbon black super P and binder PVDF in a ratio of 8:1:1, and the rest was as in example 5.
Example 8
The sample prepared in example 4 was mixed with conductive carbon black super P and binder PVDF in a ratio of 8:1:1, and the rest was as in example 5.
Comparative example 1
The AZO-coated lithium nickel manganese oxide secondary lithium battery positive electrode material is prepared according to the method disclosed in CN 102983324B.
0.5mol/L solution, drying the solution by using a spray dryer to obtain a mixture, calcining the mixture at the constant temperature of 800 ℃ for 22h in the air atmosphere, and naturally cooling to obtain a nickel manganese oxide precursor Ni0.5Mn1.5O2Mixing the nickel manganese oxide precursor and lithium hydroxide according to the molar ratio of 1:1.1, grinding, and sintering at the constant temperature of 700 ℃ for 24 hours in an air atmosphere to obtain LiNi0.5Mn1.5O4。
With Zn (CH)3COO)2·2H2O:LiNi0.5Mn1.5O4Zinc acetate and LiNi obtained in comparative example 1 were weighed so that the mass ratio of (1) to (0.05: 1)0.5Mn1.5O4Weighing aluminum nitrate according to the molar ratio of Al to Zn of 0.015 to 1, adding zinc acetate and aluminum nitrate into a certain amount of distilled water for dissolving, dropwise adding a certain amount of citric acid solution into the solution, stirring for 60min, and then adding weighed LiNi into the solution0.5Mn1.5O4Stirring the mixed solution in a 90 ℃ constant-temperature water bath for 3h to obtain a precursor, drying the obtained precursor in an air atmosphere at a constant temperature of 120 ℃ for 12h, presintering the obtained powder in an air atmosphere at a constant temperature of 700 ℃ for 4h, and naturally cooling to obtain the coated LiNi0.5Mn1.5O4Sintering the compound at the constant temperature of 900 ℃ for 8 hours in an air atmosphere to obtain 5wt% AZO coated LiNi0.5Mn1.5O4。
LiNi coated with AZO0.5Mn1.5O4. Mixing a sample, conductive carbon black super P and a binder PVDF according to a ratio of 8:1:1, dissolving the mixture in N-methylpyrrolidone (NMP), uniformly stirring the mixture, coating the mixture on an aluminum foil to prepare a positive plate, drying the positive plate in a vacuum oven at 120 ℃ for 12 hours, and assembling the dried positive plate, a negative electrode prepared from a metal lithium plate, a polypropylene diaphragm and an electrolyte in a glove box filled with high-purity argon to obtain the CR2032 type button experimental battery.
The charging multiplying power is 0.1C, the discharging multiplying power is 0.1C, 0.2C, 0.5C, 1C, 3C, 5C and 10C respectively, and the charging and discharging voltage interval is between 3 and 4.9 volts. The supporting electrolyte in the electrolyte is LiPF6The solvent is formed by mixing Ethylene Carbonate (EC) and diethyl carbonate (DEC) according to the volume ratio of 1:1, the concentration of the electrolyte is 1mol/L, and the battery testing temperature is room temperature.
FIG. 3 is a graph showing cycle characteristics of samples obtained in examples 5 to 8 and comparative example 1 at different magnifications at room temperature; FIG. 4 is a graph showing cycle characteristics at high temperature and high current of the samples obtained in examples 5 to 8 and comparative example 1. The experimental cells of examples 5-8 showed significant improvement in performance.
In light of the foregoing description of the preferred embodiments of the present invention, it is to be understood that various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the invention. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.

Claims (4)

1. The preparation method of the nanometer AZO-coated octahedral lithium nickel manganese oxide composite material is characterized by comprising the following preparation steps:
(1) soluble nickel salt and manganese salt are mixed according to the molar ratio of nickel to manganese elements of 1: 3, dissolving in deionized water in proportion, violently stirring at the constant temperature of 25-50 ℃, slowly adding a sodium hydroxide solution with the concentration of 0.5-2 mol/L to adjust the pH value of the solution to 9-12, continuously stirring for 1-4 hours at the constant temperature, and then centrifuging, washing and drying to obtain an intermediate product precursor;
(2) and (2) enabling the molar ratio of the intermediate product precursor obtained in the step (1) to lithium elements of lithium salt to be 1: 1.04-1.1, and calcining, wherein the calcining process comprises the following steps: heating to 400-600 ℃ at the speed of 1-5 ℃/min, and preserving heat for 2-6 hours; then heating to 800-950 ℃ at the speed of 1-5 ℃/min, and preserving heat for 15-25 hours; then cooling to room temperature at the speed of 1-5 ℃/min, and crushing and sieving to obtain octahedral lithium nickel manganese oxide powder;
(3) dissolving soluble zinc salt, aluminum salt and a chelating agent in an ethanol aqueous solution according to a ratio to obtain an AZO solution, wherein the amount of an aluminum ion substance accounts for 0.5-3% of the total amount of zinc ions and aluminum ions, and the ratio of the amount of the chelating agent substance to the total amount of the zinc ions and aluminum ions is (1-3): 1, the volume ratio of ethanol in the ethanol water solution is less than or equal to 50 percent; dispersing the octahedral lithium nickel manganese oxide powder obtained in the step (2) in the solution according to a proportion, wherein the mass of AZO accounts for 0.2% -2% of that of the octahedral lithium nickel manganese oxide powder, gradually adding an alkali solution into the mixed solution at a constant temperature of 50-80 ℃ to adjust the pH value of the mixed solution to 9-12, continuously stirring at the constant temperature for 1-4 h, and then centrifuging, washing and drying to obtain a final product precursor;
(4) calcining the precursor of the final product obtained in the step (3), wherein the calcining process comprises the following steps: heating to specific 400-500 ℃ from room temperature at the speed of 5-20 ℃/min, preserving the heat for 1-4 hours, and then cooling to obtain the nano AZO-coated octahedral-structure lithium nickel manganese oxide composite material.
2. The preparation method of the nano AZO-coated octahedral-structure lithium nickel manganese oxide composite material according to claim 1, characterized in that: in the step (2), the lithium salt is lithium carbonate, or lithium hydroxide hydrate.
3. The preparation method of the nano AZO-coated octahedral-structure lithium nickel manganese oxide composite material according to claim 1, characterized in that: the chelating agent in the step (3) is citric acid or citric acid hydrate.
4. The preparation method of the nano AZO-coated octahedral-structure lithium nickel manganese oxide composite material according to claim 1, characterized in that: the alkali solution in the step (3) is a sodium hydroxide solution, a potassium hydroxide solution, a lithium hydroxide solution or a mixed solution of two or three solutions.
CN201810585528.8A 2018-06-08 2018-06-08 Nano AZO-coated octahedral-structure lithium nickel manganese oxide composite material and preparation method thereof Active CN108511737B (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102983324A (en) * 2012-12-19 2013-03-20 苏州大学 Positive material of AZO-coated lithium nickel manganese oxide secondary lithium battery and preparation method of positive pole material
CN103151528A (en) * 2013-02-28 2013-06-12 天津工业大学 Method for preparing aluminum-doped zinc oxide coated lithium-ion battery positive-pole material
CN103311525A (en) * 2013-06-08 2013-09-18 深圳华粤宝电池有限公司 Preparation method of positive material of lithium-ion battery

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102983324A (en) * 2012-12-19 2013-03-20 苏州大学 Positive material of AZO-coated lithium nickel manganese oxide secondary lithium battery and preparation method of positive pole material
CN103151528A (en) * 2013-02-28 2013-06-12 天津工业大学 Method for preparing aluminum-doped zinc oxide coated lithium-ion battery positive-pole material
CN103311525A (en) * 2013-06-08 2013-09-18 深圳华粤宝电池有限公司 Preparation method of positive material of lithium-ion battery

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